In a case-control study on oral cancer, 80 out of 100 cases and 40 out of 100 controls were found to be tobacco chewers. What is the odds ratio for tobacco chewing and oral cancer?
- A 2.0
- B 6.0 ✓
- C 4.0
- D 8.0
Correct answer: B. 6.0
Explanation
The odds ratio is calculated as (a×d)/(b×c), where a=exposed cases=80, b=unexposed cases=20, c=exposed controls=40, d=unexposed controls=60. OR = (80×60)/(20×40) = 4800/800 = 6.0. An odds ratio of 6 indicates tobacco chewers have six times the odds of developing oral cancer compared to non-chewers.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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